The present invention is drawn a method for the preparation of a hydrocarbon in water emulsion from viscous hydrocarbons and, more particularly, a method for the preparation of low-viscosity hydrocarbon in water emulsions from viscous hydrocarbons wherein aging of the emulsion over time is substantially eliminated.
The viscous hydrocarbons (below 12.degree. API gravity) found in Canada, the Soviet Union, the United States, China, and Venezuela, are liquids having viscosities running from 10,000 to 500,000 centipoise at room temperature. Normally, these viscous hydrocarbons are produced by mechanical pumping alone, mechanical pumping combined with steam injection, and through mining techniques. To make hydrocarbons of this kind more commercially valuable, it is necessary to develop methods to increase the effectiveness and profitability of their transportation and storage thereby facilitating their subsequent use as raw materials in the derivation of other products or in other applications. Processes have been conceived to modify these hydrocarbons so as to change them into a pumpable form and make it possible to move them through conventional pipes. Among the most common processes is that of forming emulsions of these hydrocarbons in water. The emulsions have much lower viscosity than the hydrocarbon alone and thus can be pumped at a faster speed through the pipe lines with conventional pumping equipment.
The aforesaid emulsions are prepared using surfactants, which can be cationic, anionic, and/or non-ionic. Their preparation involves a large number of variables, both physical-chemical (covering the formulation of the emulsion) and mechanical (relating to the method and speeds of stirring). These variables are very important, since the stability of the emulsion, that is, that their component phases do not separate out and that their viscosity remains constant over time, depends upon these variables.
Several methods have been proposed for forming emulsions of hydrocarbons in water using chemical additives, thereby reducing the viscosity of the hydrocarbons so as to make them transportable.
Typical processes are described in U.S. Pat. Nos. 3,380,531; 3,467,159; 3,487,844; 3,006,354; 3,425,429; 3,467,195; 3,519,006; 3,943,954; 4,099,537; 4,108,193; 4,239,052, 4,249,554; 4,627,458; and 4,795,478. They involve the use of sodium or ammonium hydroxide, non-ionic, anionic, and cationic surfactants, or combinations thereof.
The foregoing methods produce stable emulsions from the point of view of the coalescence of their phases. However, a problem which has not been resolved to date is that of controlling or eliminating the phenomenon of aging which affects these emulsions. By aging is meant the progressive increase in the viscosity of the emulsion over time. One technique used to prevent aging involves the addition of electrolytes which involves an additional cost in the process of preparation of the emulsions.
Naturally, it would be highly desirable to provide a method for preparation of hydrocarbon in water emulsions from viscous hydrocarbons wherein aging of the emulsion over time is substantially eliminated.
Accordingly, it is the principle object of the present invention to provide a method for the preparation of hydrocarbon in water emulsions from viscous hydrocarbons wherein the aging of the emulsion over time is substantially eliminated.
It is the principle object of the present invention to provide a method as aforesaid wherein the final emulsion exhibits a viscosity of less than or equal to 1500 centipoise at 80.degree. F.
It is a further object of the present invention to provide a method for the preparation of hydrocarbon in water emulsions as aforesaid wherein the average oil droplet size in the final emulsion product is greater than or equal to 15 microns.
It is a still further object of the present invention to provide a method for the preparation of hydrocarbon in water emulsions from viscous hydrocarbons as aforesaid wherein the hydrocarbon is the natural occurring crude, tar or other natural occurring hydrocarbon or residual fuel oil characterized by a viscosity of greater than 100 centipoise at 122.degree. F. and an API gravity of greater than or equal to 16.degree. API.
Further objects and advantage of the present invention will appear hereinbelow.